The piezoelectric component is a ceramic piezoactuator with a monolithic multilayer construction. Some forms of embodiment of such multilayer actuators have porous ceramic or metallic security layers (security structures). The porous security layers act as predetermined breakage points: If there is a mechanical overload of the piezoactuator's stack, any cracks (polarizing cracks) tend to form in these security layers. By this means, the location of polarizing cracks arising in the event of polarization or in operation can be defined and channeled. These security layers can be formed from ceramic layers or from electrode layers (internal electrodes) with an increased porosity.
For making electrical contact, the internal electrodes have electrical leads to alternate lateral surface sections of the stack which are electrically insulated from each other. Applied to these surface sections are metallic coatings (external metallic coatings). Alternate internal electrodes are electrically connected in parallel via these metallic coatings.
The stack of the piezoactuator is provided with a plastic sheathing made of silicone. This plastic sheathing serves to passivate the stack. This means that the internal electrodes, which extend out to the lateral surfaces of the stack, are electrically insulated and protected against mechanical destruction by the plastic sheathing.
When the metallic coatings are being applied and when the silicone is being applied to the surface of the stack, penetration of metal, melted glass (adhesion agent of the metallic coatings) and silicone components into the porous security layer can occur. An infiltration of the said substances occurs. As a result of this infiltration an undesired electrical conductivity of the security layer or a mechanical compression stress can occur, which can be accompanied by damage to the security layer and its surroundings. This could result in a premature failure of the component.